30 years ago, the world was held hostage by a nuclear-powered Soviet spy satellite tumbling out of control in an orbit close to Earth. The spiraling spacecraft, named Cosmos 1402, was launched into low-Earth orbit on Aug. 20, 1982.

What made Cosmos particularly scary is that it carried a nuclear reactor with about 100 pounds of enriched uranium. The reactor was used to power a radar system for tracking ships.

To compare, it takes as little as 35 pounds of uranium to make a nuclear bomb.

Once the satellite completed its mission, the plan was to boost the 1,000-pound reactor section, including the fuel core, into higher orbit, where it would linger at a safe distance from Earth for many hundreds of years.

But that failed.

The main body of Cosmos began tumbling out of control on Dec. 28, 1982, after the botched attempt to jettison the reactor into high-Earth orbit.

Meanwhile, the world waited with bated breath.

An excerpt from an Associated Press article dated Jan. 6. 1982 reads: “The Pentagon says [the nuclear-powered satellite] could spread destruction and radioactivity if its broken pieces fall in a populated area. It is too early to say where it will hit.”

Most of the globe was on alert as the satellite hurtled back to our planet. Many countries mobilized helicopters, ships and army units prepared to look for radioactive debris.

The main part of the satellite plunged through the atmosphere splashing down into the Indian Ocean on the night of Jan. 23, 1983.

Nobody saw the satellite’s final re-entry since it happened so far from land. ”I don’t think we’ll ever know if any of this Cosmos reached land. That sort of material would be sitting now on the bottom of the Indian Ocean,” a Pentagon spokesperson told The New York Times a day later.

But the bigger terror remained.

The reactor section, including the fuel core, was still flying all around Earth. The concern was that some radioactive pieces could survive re-entry, instead of burning, and fall on land. This was the case in 1978, when radiation from another Soviet spy satellite was found near a lake in Canada.

It is feared that the platform of uranium 235 may come down in lumps of radioactive debris covering a fairly wide area — as the nuclear reactor of Cosmos 954 did over northern Canada in 1979.

Nations have been preparing for months in case the platform has not fully disintegrated by the time it reaches earth’s atmosphere.

Fortunately, the Soviet Union and the U.S Department of defence had a good handle on when the fuel section would come back to Earth.

The nuclear fuel core plunged into the South Atlantic Ocean, about 1,000 east of Brazil on Feb. 7, 1983.

The final segment of the satellite is believed to have burned up harmlessly into dust-like particles. The Soviets claimed that any radiation entering the atmosphere from the fragments would be within limits designated safe for humans, though reconnaissance planes were dispatched to search for increased levels of radioactivity in the atmosphere.

A study that appeared in the journal Geochemical in March 1985 reported the presence of radioactive strontium fallout in rain samples collected in Fayetteville, Arkansas, between February and June 1983, believed to have come from the burn-up of Cosmos 1402.